This invention relates to a fuel injection nozzle for atomizing and spraying each metered charge of fuel, premixed with air, into the combustion chamber of a cylinder in an internal combustion engine such as, typically, a diesel engine.
Some early diesel engines employed an air-injection system, such that the fuel was atomized into the cylinder under air pressure. Although the system admittedly provided excellent smoke-free combustion, it required expensive and bulky multistage compressors and intercoolers for injection air. Consequently, with the advent of spray nozzles capable of sufficiently atomizing the fuel by use of fuel pressure alone, the solid or airless injection has become the generally accepted method of fuel injection in compression-ignition engines.
Recently, however, it is being contemplated to inject fuel into diesel engine cylinders at pressures in the order of 1000 kgf/cm.sup.2, with a view to higher engine efficiency and minimal exhaustion of air pollutants. The usual airless injection method does not necessarily provide good combustion at such ultrahigh pressures.